It is desirable that, prior to the start or restart of ventilation to a patient requiring respiration assistance, that the integrity of the circuit be validated. This includes that the circuit is intact, connected, and the right patient interface component is attached. This will assure that the ventilator delivers the appropriate set of breathing gases without gas leakage. It is also advantageous that a humidifier and bacteria filter be attached to ensure gases breathed by the patient are humidified and cross contamination is prevented. In volume controlled ventilation, some gas volumes delivered by the ventilator is absorbed in a compliant breathing circuit, or circuit component such as a humidifier, filters, HME, resulting in less tidal volume delivered to the patient. Breathing circuits come in different lengths with correspondingly different compliance values. Present methods to compensate gas volume losses is to inject a known gas volume and measure the total circuit compliance prior to the start of ventilation, or enter the type of circuit elements with their compliances or predefined compliances summing them together to obtain the total compliance. These are tedious and require additional steps by the user to enter the right information, enter the total circuit compliance and compensate for the volumes not delivered to the patient.
Current solutions detect circuit disconnects by detecting gas leakage or failure to pressurize the breathing circuit during ventilation. A common approach to detect disconnects in other industries is to provide a parallel loop back connection to test the integrity of the connected circuit. Loop-back connection can be done via electrical, pneumatic or optical leads that run the length of the breathing circuit. A weakness in this solution is it does not report what is connected and where. The introduction of electrical wires, tubes or optical fiber glass running along the gas flow passage of the breathing circuit components can be costly and intrusive. Another weakness, particularly in anesthesia ventilation, is the failure to detect reconnection of the breathing circuit. A test procedure must be conducted prior to start of ventilation to compute total compliance and resistance to provide compensation for compliance and resistance losses. This is time consuming and has to be added to the user workflow.